Electron tube

ABSTRACT

In an electron tube  1 , a space S between a periphery part  15   b  of a semiconductor device  15  and a stem  11  is filled with an insulating resin  20 . The insulating resin  20  functions as a reinforcing member while the electron tube  1  is assembled under high-temperature condition, thereby preventing a bump  16  from coming off a bump connection portion  19 . Since the space S is only partly closed by the resin  20 , the space between the semiconductor device  15  and the stem  11  is ensured a ventilability. That is, no air reservoir is formed between an electron incidence part  15   a  at the center of the semiconductor device  15  and the surface C of the stem  11 , whereby air expanding at high temperature does not damage the electron incidence part  15   a  of the back-illuminated semiconductor device  15.

TECHNICAL FIELD

The present invention relates to a highly sensitive electron tube forquantitatively measuring an extremely weak light.

BACKGROUND ART

This field of technology is described in Japanese Patent Publication No.HEI-7-95434, for example. An electron tube described in this publicationhas a package, in which a charge coupled device (CCD) of aback-illuminated type is provided. In this type of electron tube,electron emitted from a photocathode in response to an incidence oflight is directed into a back side of a device formation surface todetect a signal. This electron tube is widely used because of its highsensitivity and its high imaging quality.

An imaging device employing a back-illuminated type semiconductor deviceis described in Japanese unexamined patent application publication No.HEI-6-29506. The semiconductor device is fixed on a substrate whosethermal expansion coefficient is equal to that of the semiconductordevice. A plurality of metal bumps are formed on the semiconductordevice, each bump being connected to a metal wiring formed on thesubstrate (silicon wafer). The space between the semiconductor deviceand the substrate is filled with a nonconductive resin to preventsilicon etchant from entering therein. Since the space is filled priorto thinning of the semiconductor device, the resin has to not includealkali metal, has to have a suitable contraction stress during curing tomaintain sufficient contact of the bonding part of the bumps, and has tobe able to withstand heat up to about 150° C. during die-bonding andwire-bonding.

However, conventional electron tubes and imaging devices have thefollowing problems due to the construction described above.

In the electron tube described in Japanese patent publication No.HEI-7-95434, the semiconductor device is fixed to the stem by bondingmetal pads to contacts. However, the metal pads have a tendency to slipoff the contacts to lose a sufficient connection when the electron tubeis assembled under a high-temperature environment.

In the imaging device described in Japanese unexamined patentapplication publication No. HEI-6-29506, the semiconductor device isthinned with etchant after the semiconductor device is fixed to thesubstrate. Accordingly, the space between the semiconductor device andthe substrate is completely filled with resin in order to prevent anyetchant from entering therein. Since the resin is attached directly onthe electron incidence part of the semiconductor device, stress isgenerated in the electron incidence part when the resin cures orhardens. The electron incidence part runs the risk of becoming deformed,resulting in poor images, or in some cases broken.

In view of the foregoing, it is an object of the present invention tosolve the above-described problems and to provide an electron tube whichis capable of avoiding poor connections that can occur during theassembly process, as well as deformation or damage to the.semiconductordevice that can also occur during this process.

DISCLOSURE OF THE INVENTION

These objects and others will be attained by an electron tube,comprising: a side tube; a faceplate provided at one end of the sidetube and having a photocathode that emits electrons in response toincident light; a stem provided at the other end of the side tube, thestem and the faceplate defining a vacuum region, the stem having a bumpconnection portion on its surface; and a semiconductor device fixed tothe stem at its vacuum side, the semiconductor device having a frontsurface positioned on the stem side and a back surface positioned on thefaceplate side, the semiconductor device including an electron incidencepart, for receiving electrons emitted from the photocathode, and aperiphery part provided at an outer periphery of the electron incidencepart, the electron incidence part having a thin plate shape whosethickness is smaller than that of the periphery part, the periphery parthaving a bump which protrudes from the front surface thereof the bumpbeing fixed to the bump connection portion, the bump forming a spacebetween the front surface of the semiconductor device and the surface ofthe stem, a filling material with insulation property being filledpartially in the space at the periphery part, thereby partially closingthe space at the periphery part.

Hence, the electron tube of the present invention includes: a side tube;a faceplate provided at one end of the side tube and having aphotocathode that emits electrons in response to incident light; a stemprovided at the other end of the side tube, the stem and the faceplatedefining a vacuum region; and a semiconductor device fixed to theevacuated side of the stem and having an electron incidence part forreceiving electrons emitted from the photocathode. The semiconductordevice is configured as a back-illuminated type semiconductor device.That is, the semiconductor device has a front surface positioned on thestem side and a back surface positioned on the faceplate side. Thesemiconductor device has a plate-shaped electron incidence part that isformed thinner than the periphery part which is formed around theelectron incidence part. A bump is formed to protrude from the frontsurface of the periphery part. The bump is fixed to a bump connectionportion provided on the surface of the stem. The bump forms a spacebetween the front surface of the semiconductor device and the surface ofthe stem. The space at the periphery part is partially filled with afilling material with insulating properties. Accordingly, the space atthe periphery part is partially closed with the filling material havinginsulating properties.

Accordingly, in the electron tube of the present invention, insulatingfilling material is filled partially in the space between the peripherypart of the semiconductor device and the stem, while the bump formed onthe semiconductor device is connected to the bump connection portionprovided on the surface of the stem. Hence, the filling materialfunctions as a reinforcing member to prevent the bump from separatingfrom the bump connection portion even when the electron tube isassembled under a high-temperature environment.

The space defined at the periphery of the semiconductor device is filledwith insulating filling material, while the space defined at theelectron incidence part is not filled with the insulating fillingmaterial. Accordingly, there is no danger of the electron incidence partbecoming deformed or damaged due to stress generated when the insulatingfilling material is hardened.

Further, ventilation between the semiconductor device and the stem isensured because the space between the semiconductor device and stem isonly partially closed by the filling material. If the entirecircumference of the periphery part of the semiconductor device werecompletely closed by the filling material, an air reservoir would beformed between the electron incidence part and the surface of the stem.During the process of assembling the electron tube in a vacuum, this airwould expand and could cause damage to the electron incidence part whichis formed as a thin plate on the back-illuminated semiconductor device.Contrarily, the present invention enables air to flow between thesemiconductor device and the stem, ensuring that air can be evacuated inthe vacuum environment when the electron tube is assembled.

Thus, according to the present invention, the bump protruding from thefront surface of the periphery part of the semiconductor device is fixedto the bump connection portion which is provided on the surface of thestem. This bump forms the space between the front surface of thesemiconductor device and the surface of the stem. The space along theperiphery part of the semiconductor device is partially filled with afilling material with insulation properties. Accordingly, the space isclosed only partially with the insulating filling material. As a result,it is possible to prevent poor bump connection that can possibly arisewhen the electron tube is assembled and to prevent damage to thesemiconductor device that can occur during the same process.

The filling material with insulation property may preferably be filledin the space at the periphery part of the semiconductor device exceptfor at least one position along the entire circumference of theperiphery part, thereby allowing the space at the periphery part to befilled with the filling material with insulation property except for theat least one position.

For example, the filling material with insulation property maypreferably be filled in the space at at least one position along theentire circumference of the periphery part of the semiconductor device,with a ventilating region being formed in at least one position alongthe entire circumference of the periphery part of the semiconductordevice to provide fluid communication between the space and the vacuumregion. With this construction, it is possible to avoid, by theinsulating filling material, poor bump connection which can be causedwhen the electron tube is assembled, and to eliminate damage to thesemiconductor device that can occur during the same process by ensuringventilation through the ventilating region.

The filling material may have an electrically insulating material. Thefilling material may have a melting characteristic, but when heated, thefilling material may be hardened and contract at an appropriatecontraction stress to adhere to a surrounding material. An insulatingresin is preferable as the insulating filling material. However, waterglass or low-melting glass can be used.

Additionally, the stem may preferably have a supporting substrate on itssurface, the supporting substrate being formed of the same siliconmaterial as a base material of the semiconductor device, the bumpconnection portion being provided on the supporting substrate. With thisconfiguration, the thermal expansion coefficient of the supportingsubstrate which has the bump connection portion can be.madeapproximately equal to that of the semiconductor device which has thebump. Therefore, the bump will not separate from the bump connectionportion during the baking (heating) process in the electron tubemanufacturing process, thereby maintaining a better connection state.

The bump may preferably be made of material that includes gold as aprimary component. When the bump is made of material whose primarycomponent is gold, the bump does not melt during the baking process inthe manufacturing process. Further, because the insulating material,which is filled partially in the space between the periphery part of thesemiconductor device and the stem, serves as a reinforcing material, theinsulating material can prevent breakage in the bump, whose maincomponent is gold, during the baking process.

The stem may have, at its surface, a channel for controlling the partialfilling of the filling material with insulating property into the spaceat the periphery part. With this configuration, it is possible to allowan excess insulating filling material to flow into the channel when theinsulating filling material is introduced from outside the peripherypart into the space between the periphery part of the semiconductordevice and the stem. Therefore, it is possible to prevent the insulatingfilling material from being attached to the electron incidence part ofthe semiconductor device, eliminating the possibility of the electronincidence part becoming damaged when the filling material cures orhardens. Accordingly, the filling of the insulating material can beattained appropriately without precisely controlling the amount of theinsulating filling material. Especially, when the space between thesemiconductor device and the stem is extremely narrow, the capillaryeffect can be used to force the insulating filling material to flow intothe space. The excess insulating filling material automatically flowsinto the channel. Accordingly, control of the flow can be made easy andefficient.

For example, the channel may preferably have a width that allows thechannel to span across a border between the periphery part and theelectron incidence part. When the channel, whose width has a value toallow the channel to span across the border between the periphery partand the electron incident part, is formed on the surface of the stem, inorder to fill the insulating filling material into the space between theperiphery part of the semiconductor device and the stem, it is possibleto introduce the filling material from outside the periphery part whileletting the excess filling material to flow into the channel. It istherefore possible to easily prevent the filling material from attachingthe electron incidence part. Especially when the space is extremelynarrow, the capillary effect can be employed to draw the fillingmaterial into the space, making the process for introducing the fillingmaterial easy and efficient. When the width of the channel is set at asize to span across the border between the periphery part and theelectron incidence part, several channels can be formed individually incorrespondence with several regions to be filled with the fillingmaterial.

The channel may preferably be formed at a region that faces theperiphery part only. When the channel is formed on the surface of thestem to confront only the periphery part, in order to fill theinsulating filling material in the space between the periphery part ofthe semiconductor device and the stem, it is possible to introduce thefilling material into the space from outside the periphery part whileallowing an excess filling material to flow into the channel. It istherefore possible to easily prevent the filling material from attachingthe electron incidence part. Especially when the space is extremelynarrow, the capillary effect can be employed to draw the fillingmaterial into the space, making the process for introducing the fillingmaterial easy and efficient. In addition, the initial objective can beattained simply by forming the channel to correspond only to theperiphery part.

The channel may preferably have a width that allows the channel to spanacross one side portion of the periphery part and the other opposingside portion of the periphery part. When the channel, whose width canallow the channel to span across one side portion of the periphery partand the other opposing side portion of the periphery part, is formed onthe surface of the stem, in order to fill the insulating fillingmaterial in the space between the periphery part of the semiconductordevice and the stem, it is possible to introduce the filling materialinto the space from outside the periphery part while allowing an excessfilling material to flow into the channel. It is therefore possible toeasily prevent the filling material from attaching the electronincidence part. Especially when the space is extremely narrow, thecapillary effect can be employed to draw the filling material into thespace, making the process for introducing the filling material easy andefficient. In addition, when the width of the channel is set to spanacross one side portion of the periphery part and the other opposingside portion in this way, it is possible to form a channel thatcorresponds to the size and shape of the electron incidence part of thesemiconductor device.

The space formed by the bump may preferably have, at the periphery part,a height small enough to allow the filling material with insulationproperty to generate a capillary effect.when the filling material isdrawn into the periphery part, the channel having a depth of an amountthat is capable of stopping the filling material that flows due to thecapillary effect. With this construction, when the filling materialflowing according to the capillary effect reaches the edge of thechannel, the filling material does not enter the channel but collectsalong the edge due to surface tension in the material. Therefore, thefilling material can be easily drawn into the space and, at the sametime, can be easily and effectively prevented from attaching theelectron incidence part of the semiconductor device.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a cross-sectional view showing an electron tube according to afirst embodiment of the present invention;

FIG. 2 is an enlarged cross-sectional view showing a portion where thesemiconductor device is bonded to the stem of the electron tubeaccording to the first embodiment;

FIG. 3 is plan and side views showing the semiconductor device used inthe electron tube of the first embodiment;

FIG. 4 is a cross-sectional view showing the semiconductor device usedin the electron tube of the first embodiment;

FIG. 5 is an enlarged view of aluminum wirings provided in thesemiconductor device used in the electron tube of the first embodiment;

FIG. 6 is an enlarged perspective view showing a bonding pad and a bumpused in the electron tube of the first embodiment;

FIG. 7 is an enlarged cross-sectional view of an essential portion ofFIG. 2, showing how a bump on the semiconductor device is bonded to abump connection portion on the stem in the electron tube of the firstembodiment;

FIG. 8 is a plan view of a bonded portion of the semiconductor device,showing a channel provided on the electron tube of the first embodiment;

FIG. 9 is a cross-sectional view showing an electron tube according to asecond embodiment;

FIG. 10 is an enlarged cross-sectional view showing the portion wherethe semiconductor device is bonded to a supporting substrate of theelectron tube according to the second embodiment;

FIG. 11 is a plan view showing the portion where the semiconductordevice is bonded to the supporting substrate with a channel according tothe second embodiment;

FIG. 12 is an enlarged cross-sectional view showing an essential portionof an electron tube according to a third embodiment;

FIG. 13 is an enlarged cross-sectional view showing the portion wherethe semiconductor device is bonded to the supporting substrate of theelectron tube according to a modification of the embodiments; and

FIG. 14 is a plan view showing the portion where the semiconductordevice is bonded to the supporting substrate according to a modificationof the electron tube of the embodiments.

BEST MODE FOR CARRYING OUT THE INVENTION

An electron tube according to preferred embodiments of the presentinvention will be described while referring to FIGS. 1-12.

First, an electron tube according to a first embodiment will bedescribed with reference to FIGS. 1-8.

FIG. 1 is a cross-sectional view showing an electron tube 1 according tothe first embodiment of the present invention. The electron tube 1 is ofa proximity focusing type in which a photocathode is positioned near toa semiconductor device. The electron tube 1 includes a side tube 2having two open ends 2 a and 2 b. A substantially. disc-shaped faceplate8 is bonded to the open end 2 a, and a similarly substantiallydisc-shaped stem 11 is bonded to the open end 2 b, to provide a sealedstructure in which a vacuum region R is provided. A photocathode 9 isformed over the surface of the faceplate 8 on the vacuum region R side,while a semiconductor device (CCD device) 15 is fixed to the stem 11 onthe vacuum region R side, thereby achieving the functions of an electrontube.

The side tube 2 has a cylindrical shape with an external diameter ofapproximately 43 mm, for example. The side tube 2 has a ring-shaped bulb3 which is made of an electrically insulating material, such as ceramic.The bulb 3 includes a first bulb 3A, a second bulb 3B, and a flangeportion 7. The flange portion 7 is made of Koval metal, and isinterposed between the first and second bulbs 3A and 3B. The three partsare constructed integrally into the bulb 3 through brazing. An annularcathode electrode 5 is provided in the opening on the first bulb 3A side(the first open end 2 a), while an annular welding electrode 6 isprovided in the opening on the second bulb 3B side (the second open end2 b). The cathode electrode 5 and the welding electrode 6 are brazed tothe bulb 3 to form an integral unit. The cathode electrode 5 is in agutter shape for collecting indium material 4. The indium material 4serves as an adhesive agent for bonding the side tube 2 to the faceplate8 and as a sealing member for creating the vacuum region R. The cathodeelectrode 5 can supply an electric voltage to be applied to thephotocathode 9.

The faceplate 8 made of Koval glass is disposed over the first open end2 a. The faceplate 8 has a protruded portion 8 a at its center portion.The faceplate 8 is fixed and sealed to the cathode electrode 5 via theindium material 4. A photocathode 9 is formed on the inner surface ofthe faceplate 8. The photocathode 9 is for emitting electrons into thevacuum region in response to incidence of light. A photocathodeelectrode 10 is formed on the faceplate 8 around the photocathode 9. Thephotocathode electrode 10 is made of a chrome thin film, and isdeposited onto the faceplate 8. The photocathode electrode 10electrically connects the photocathode 9 with the indium material 4.

The faceplate 8 and the stem 11, which is fixed over the second open end2 b of the side tube 2, define the vacuum region R. The stem 11includes: a four-layered base plate 12 formed of ceramic; and a metalflange 13 which is fixed to the base plate 12 by brazing. Theback-illuminated type semiconductor device 15, having a siliconsubstrate as its base material, is fixed to a surface C (see FIG. 2) ofa base plate 12 a, which is the uppermost layer of the base plate 12. Asshown in FIG. 1, a plurality of stem pins 14 are fixed to a base plate12 d, which is the lowermost layer of the base plate 12, for applyingdrive signals to the semiconductor device 15 from an external device andfor outputting signals outputted from the semiconductor device 15 to anexternal device. Internal wirings or leads (not shown) are providedwithin the base plate 12 for electrically connecting the semiconductordevice 15 with the stem pins 14. The internal wirings transmit drivesignals, applied to the stem pins 14, to the semiconductor device 15,and transmit signals, outputted from the semiconductor device 15, to thestem pins 14. The side tube 2 and the stem 11 are formed as an integralunit by arc welding the metal flange 13 and the welding electrode 6together. A getter G is fixed to the inner wall of the side tube 2. Thegetter G is for absorbing residual gas in the electron tube. This getterG is connected between the welding electrode 6 and the flange portion 7.

As shown in FIGS. 1 and 2, the semiconductor device 15 has an electronincidence part 15 a at its central part. The semiconductor device 15 isdisposed near the photocathode 9 at a distance of approximately 1millimeter. Electrons emitted from the photocathode 9 fall incident onthe electron incidence part 15 a. The semiconductor device 15 isconfigured as a back-illuminated type semiconductor device, and a frontsurface A (device-formed surface) of the semiconductor device 15 ispositioned on the base plate 12 (stem 11) side, while a back surface Bof the semiconductor device 15 is positioned on the faceplate 8 side.The electron incidence part 15 a is formed thinner than a rectangularperiphery part 15 b (see FIGS. 3 and 8), which is provided around theelectron incidence part 15 a, in order to achieve the back-illuminatedfunction of the semiconductor device 15. A chemical etching process isemployed to form the electron incidence part 15 a into a thin plate ofapproximately 20 μm thickness, while remaining the periphery part 15 b.

FIG. 2 is a cross-sectional view showing the portion where thesemiconductor device 15 is bonded to the uppermost base plate layer 12a. As will be described later, a plurality of bumps 16 are provided viabonding pads 17 on the front surface A of the periphery part 15 b. Thebumps 16 serve as electrodes. A plurality of bump connection portions 19are formed on the upper surface C of the base plate 12 a at positionswhere the bump connection portions 19 can connect with the bumps 16.Thus, the semiconductor device 15 and the base plate 12 a aremechanically and electrically connected via the bonding pads 17, thebumps 16, and the bump connection portions 19. A conductive resin 18(see FIG. 7) is provided around each bump 16 to prevent electricaldisconnections of the bump 16. The area surrounding the conductive resin18 is filled with an insulating resin 20 to reinforce the connectionbetween the semiconductor device 15 and the base plate 12 a.

The internal wirings (not shown) are provided inside the base plate 12.The internal wirings are for electrically connecting each bumpconnection portion 19, which is connected to the corresponding bump 16,to the corresponding stem pin 14 (see FIG. 1). The positions of therespective bump connection portions 19 on the surface C of the baseplate 12 a are offset from the positions of the corresponding stem pins14 on the base plate 12 d. Accordingly, internal wirings (not shown)provided in the intermediate base plates 12 b and 12 c, which serve asthe second and third layers of the base plate 12, are connected witheach other, while being offset at a prescribed pitch. With thisconstruction, each bump connection portion 19 on the surface of the baseplate 12 a is connected appropriately to the corresponding stem pin 14.A drive signal applied to one stem pin 14 is properly guided to thecorresponding bump 16 via the corresponding bump connection portion 19.Signals outputted from the semiconductor device 15 to one bump 16 areproperly guided to the corresponding stem pin 14 via the correspondingbump connection portion 19.

Next, the structure of the semiconductor device 15 will be described ingreater detail.

As shown in FIG. 3, a CCD is formed on the front surface A side of thesemiconductor device 15. The semiconductor device 15 is formed into athin plate by chemically etching the silicon substrate on the backsurface B side of the semiconductor device 15 while remaining theperiphery part 15 b.

More specifically, an electron incidence part 15A is formed in thecenter portion of the back surface B as shown in FIG. 3. A chargehorizontal transfer portion 60 and a charge vertical transfer portion 62are formed on the front surface A. The charge horizontal transferportion 60 and the charge vertical transfer portion 62 are for readingcharge incident on the electron incidence part 15A and for transferringthe charge to an external circuit. In FIG. 3, 82 designates an FETportion, 86 designates a conductive aluminum wire or lead, 96 designatesa connection portion connected to a substrate (64) of the CCD, 98designates a reset gate terminal, 100 designates a reset drain terminal,102 designates an output drain terminal, and 104 designates an outputsource terminal. A description of these parts are omitted because theparts are individually well known in the art.

FIG. 4 shows a cross-section of the semiconductor device 15 taken alongthe line X in FIG. 3. A semiconductor substrate 64, which is the basematerial making up the semiconductor device 15, is formed of a P-type oran N-type silicon. The central section of the semiconductor wafer 64 isformed thinner than the periphery part. An epitaxial layer 63 having adifferent impurity concentration than that is of the semiconductor wafer64 is formed on the front surface A side of the semiconductor wafer 64.The CCD of the semiconductor device 15 is formed on the epitaxial layer63 side. More specifically, a buried layer 66, which provides theopposite conductive property against the semiconductor substrate 64, isformed on the epitaxial layer 63. Barrier regions 68 having an impurityconcentration different from that of the buried layer 66 are formed byintroducing impurities at prescribed positions in the buried layer 66.Storage electrode layers 72, transfer electrode layers 74, and barrierelectrode layers 76 are formed as partly overlapping with one anotherwith an SiO₂ layer 70 interposing between the layers.

On the front surface A side of the semiconductor device 15, a PSG film78 (leveling film) is formed over the entire front surface A of thesemiconductor device 15 to form a level surface on the semiconductordevice 15. The PSG film 78 (leveling film) is made of phosphosilicateglass (hereinafter referred to as PSG). Contact holes 84 are formed inthe PSG layer 78 at positions above terminals, such as electrodes 80 ofthe charge horizontal transfer portion 60 and the charge verticaltransfer portion 62 and the FET portions 82. These terminals areelectrically connected to the aluminum wires 86 which are formed on thePSG layer 78 through the contact holes 84. An SiN film 106 (thin film)described later is formed over the top of the PSG layer 78.

FIG. 5 schematically shows the configuration of the aluminum wires 86and the contact holes 84 in the charge horizontal transfer portion 60.The aluminum wires 86 are formed to cover the contact holes 84, therebyestablishing electrical connection between the terminals of the chargetransfer portion and the aluminum wires 86. Here, terminals refer to thelocations at which the aluminum wires 86 passing through the contactholes 84 connect with portions of the charge horizontal transfer portion60 and the charge vertical transfer portion 62.

As shown in FIG. 3, the aluminum wires 86 formed on the PSG layer 78 areelectrically connected to the charge horizontal transfer portion 60, thecharge vertical transfer portion 62, the substrate connection portion96, the reset gate terminal 98, the reset drain terminal 100, the outputdrain terminal 102, the output source terminal 104, and the like. Thealuminum wires 86 are provided with a plurality of bumps 16 (electrodes)at a plurality of locations on the periphery part 15 b. The bumps 16 areconnected to the bump connection portions 19 on the base plate 12 a.More specifically, the rectangular peripheral part 15 a has four sideportions 15 b 1, 15 b 2, 15 b 3, and 15 b 4, and the aluminum wires 86have a plurality of end portions on two of the four side portions 15 b1, 15 b 2, 15 b 3, and 15 b 4, that is, on the two opposing sideportions 15 b 2 and 15 b 4. As shown in FIG. 6, at each end portion, thealuminum wire 86 has a bonding pad 17 which has a larger area than thealuminum wire 86. A bump protrusion 16 made of gold (Au) is formed by Audeposition on each bonding pad 17.

The SiN film 106 is mainly made of SiN. As shown in FIG. 4, the SiN film106 is formed over the entire front surface A on top of the PSG layer 78and the aluminum wires 86. As shown in FIG. 7, the SiN layer 106 arepartly removed at positions that correspond to the bonding pads 17 toexpose the bonding pads 17 and the bumps 16. In this way, the exposedbumps 16 form electrodes for maintaining electrical connection with thebump connection portions 19 on the base plate 12 a.

With this construction, a plurality of aluminum wiring end portions(pads) 17 are formed on the front surface A in two opposing rows on theperiphery part 15 b of the semiconductor device 15, as shown in FIG. 3.As shown in FIG. 7, the bump 16 having Au (gold) as its main or primarycomponent protrudes from each bonding pad 17. This type of metal bump 16does not melt even when it is applied with heat of approximately 300° C.during the baking (heating) process in the electron tube manufacturingprocess.

As shown in FIG. 7, a plurality of Au (gold) bump connection portions 19are formed on the surface C of the base plate 12 a in the stem 11. Theplurality of Au (gold) bump connection portions 19 serve as part of thewirings to the stem pins 14. The semiconductor device 15 is positionedfacing the base plate 12 a such that each bump 16 opposes thecorresponding bump connection portion 19. A conductive resin 18 (such asa polymer adhesive) of paste form is applied around each bump 16. Thisconductive resin 18 alleviates stress deformation which is caused bydifference in thermal expansion coefficients that results from thedifference in material of the semiconductor device 15 and of the stem11, thereby preventing breaks or disconnections of the bump 16 duringthe baking process. With this construction, the bump 16 is electricallyand mechanically connected with the bump connection portion 19 via theconductive resin 18.

By fixing the bumps 16 to the bump connection portions 19 as describedabove, a space or gap S approximately corresponding to the height of thebumps 16 is formed between the front surface A of the semiconductordevice 15 and the surface C of the base plate 12 as shown in FIG. 7.This space S is filled, at the periphery part 15 b of the semiconductordevice 15, with the insulating resin 20, such as a polymer adhesive, inthe paste form. The insulating resin 20 is an adhesive agent used inmicroelectronics and has an adhesive tolerance of 400° C. or lower.After the space S in the periphery part 15 b is filled with theinsulating resin 20, the insulating resin 20 is cured or hardened. Theinsulating resin 20 functions as a reinforcing member when the electrontube 1 is assembled in a high-temperature environment (approximately300° C.). The insulating resin 20 firmly fixes the.semiconductor device15 to the stem 11, preventing the bumps 16 from separating from the bumpconnection portions 19. Since the insulating resin 20 does not enter theelectron incidence part 15 a, the electron incidence part 15 a is notdeformed or damaged by stress which is generated when the insulatingresin 20 is cured.

FIG. 8 shows the portion where the semiconductor device 15 is bonded tothe base plate 12 a in the manner described above. The plurality ofbumps 16, which are mainly made of gold, are formed on the front surfaceA in two opposing rows at the rectangular periphery part 15 b of thesemiconductor device 15. The insulating resin 20 is provided to each rowof bumps 16. More specifically, each of the opposing two side portions15 b 2 and 15 b 4, in the four side portions 15 b 1, 15 b 2, 15 b 3, and15 b 4 of the periphery part 15 b, encloses the corresponding row ofbumps 16. The insulating resin 20 is filled in the space S of theperiphery part 15 b at a position around each bump 16 in each of theside portions 15 b 2 and 15 b 4. The insulating resin 20 is not providedon the other side portions 15 b 1 and 15 b 3, which contain no bumps 16.As a result, the space S is partially closed by the insulating resin 20without closing the entire circumference of the periphery part 15 b.

By partially closing the space S with the insulating resin 20 in thisway, a ventilating region 22 not filled with insulating resin 20 isformed in the space S along the circumference of the periphery part 15b, allowing the passage of air between the semiconductor device 15 andthe stem 11. More specifically, the ventilating region 22 is formed onthe two side portions 15 b 1 and 15 b 3 that have no bumps 16.Accordingly, the space S between the electron incidence part 15 a of thesemiconductor device 15 and the stem 11 is in fluid communication withthe vacuum region R inside the electron tube 1.

If the entire circumference of the periphery part 15 b were filled incompletely by the insulating resin 20, an air reservoir would be formedbetween the electron incidence part 15 a disposed in the center of thesemiconductor device 15 and the surface C of the base plate 12. Sincethe air in this air reservoir would expand when the stem 11 is placed ina vacuum during the assembly process, there is a risk that the thinelectron incidence part 15 a may become damaged. Therefore, theconstruction of the present embodiment enables air to pass between thesemiconductor device 15 and the stem 11, allowing air to be evacuatedfrom this region when the electron tube 1 is assembled in a transferdevice. Further, evacuation can be conducted smoothly because twoventilating regions 22 are formed opposite each other on either side ofthe space S formed between the electron incidence part 15 a and the stem11.

As shown in FIGS. 1, 2, and 8, a rectangular channel or groove 21 isformed on the surface C of the base plate 12 a opposing the electronincidence part 15 a. The channel 21 functions to control filling of theinsulating resin 20. The channel 21 is formed to have: a width W thatspans across one side portion (side portion 15 b 2 that contains a rowof bumps 16) of the periphery part 15 b and the opposing side portion(side portion 15 b 4 that contains the other row of bumps 16) of theperiphery part 15 b, and a length L that extends beyond the outer edgesof both of the other opposing side portions (side portions 15 b 1 and 15b 3 that contain no rows of bumps 16) of the periphery part 15 b. Here,the width W of the channel 21 is greater than a width w of the electronincidence part 15 a (W>w), while the length L of the channel 21 islonger than the length L15 of the semiconductor device 15 (L>L15). Therectangular channel 21 therefore surrounds the entire region of theelectron incidence part 15 a. While the insulating resin 20 is suppliedfrom outside the periphery part 15 b to fill the space S between theperiphery part 15 b and the base plate 12, any excess insulating resin20 can flow into the rectangular channel 21 that has the structuredescribed above, thereby reliably avoiding the insulating resin 20 frombecoming attached to the electron incidence part 15 a. Therefore, thefilling of the insulating resin 20 can be appropriately attained, evenwhen the setting of the amount of filler and the filling operation isnot conducted with high precision.

By setting the height of the space S to about 50 μm, an extremely narrowdimension, the insulating resin 20 will flow into the space S due to itscapillary effect. In this way, it becomes easy and efficient to draw theinsulating resin 20 into the space S. In this case, it is desirable toset the depth of the rectangular channel 21 to about 0.5 mm in order toblock or stop the insulating resin 20 that flows by the capillaryeffect. When the insulating resin 20 flowing through the space S by thecapillary effect reaches the rectangular channel 21, the surface tensionof the resin material causes the material to collect along the edge ofthe rectangular channel 21 rather than entering into the rectangularchannel 21. Accordingly, the insulating resin 20 can be reliablyprevented from being attached on the electron incidence part 15 a.Hence, the process of filling the insulating resin 20 can be performedeasily and appropriately.

The rectangular channel 21 also has a length L so that the rectangularchannel 21 can extend beyond the outer edges of the opposing sideportions, which have no bumps 16, of the periphery part 15 b, therebyproviding openings 21 a in the rectangular channel 21. When assemblingthe electron tube 1 inside a transfer device, therefore, air in therectangular channel 21 escapes not only in the lateral direction via thenarrow space S, but also in the upward direction through the openings 21a, achieving superb airflow. By forming the rectangular channel 21 at asize large enough to encircle the electron incidence part 15 a, it ispossible to reliably prevent insulating resin 20 from becoming attachedon the electron incidence part 15 a.

Next, a brief description will be given for the assembly procedure ofthe electron tube 1.

First, a semiconductor device 15 having the construction shown in FIG. 3is positioned on the base plate 12 of the stem 11. The bumps 16 and thebump connection portions 19 are pressed together with an interposedconductive resin 18, and are heated at about 150° C. The bumps 16 andthe bump connection portions 19 are connected together when the solventin the conductive resin 18 is volatilized.

Next, the space S between the periphery part 15 b and the stem 11 isselectively filled with a paste-shaped insulating resin 20. Whenintroducing the insulating resin 20 toward the bumps 16 from outside theperiphery part 15 b, the capillary effect draws the insulating resin 20into the space S. At this time, the insulating resin 20 is blocked bythe rectangular channel 21 and does not become attached on the electronincidence part 15 a. If the space between the electron incidence part 15a and the base plate 12 were filled with insulating resin 20, the stressgenerated when the insulating resin 20 hardens would deform the electronincidence part 15 a, making it impossible to achieve qualitty imageswith the semiconductor device 15. The present embodiment avoids thisproblem by reliably preventing the insulating resin 20 from becomingattached on the electron incidence part 15 a. After fixing thesemiconductor device 15 to the stem 11 in this way, the side tube 2 andthe stem 11 are integrated into one piece by arc-welding the metalflange 13 of the stem 11 to the welding electrode 6 of the side tube 2.

As described above, according to the electron tube 1 of the presentinvention, there is no need to thin the semiconductor device by etchingor the like after the semiconductor device 15 is fixed to the stem 11.It is sufficient to merely fix the completed semiconductor device 15 tothe stem 11. The semiconductor device 15, the stem 11, and the likeneeded to manufacture the electron tube 1 may be mass-produced inadvance. The electron tube 1 is then assembled by fixing these partsaccording to the above-described method, thereby facilitatingmass-production of the electron tube 1.

Subsequently, the side tube 2 fixed with the stem 11, and the faceplate8, onto which the photocathode electrode 10 of a chrome thin film isdeposited, are introduced into the transfer device. The inside of thetransfer device is brought into a vacuum state. The components areassembled together into the electron tube 1 in the vacuum state insidethe transfer device. At this time, the space S between the semiconductordevice 15 and the stem 11 is only partially closed by the insulatingresin 20, preserving ventilation therebetween. That is, the space Sbetween the semiconductor device 15 and the stem 11 is in fluidcommunication with the inside of the transfer device via the ventilatingregions 22 and the openings 21 a. Therefore, when evacuating thetransfer device, air in the space S is properly discharged withoutforming an air reservoir between the electron incidence part 15 a andthe surface C of the base plate 12.

Next, the inside of the transfer device is heated (baked) toapproximately 300° C., and the photocathode 9 composed mainly of K, Cs,and Na is formed on the faceplate 8. Even if gas is emitted during thisbaking process from the insulating resin 20 into the space S between thesemiconductor device 15 and stem 11, such gas is not trapped inside thespace S, but is discharged via the ventilating regions 22 and theopenings 21 a.

Subsequently, the faceplate 8 is fixed and sealed to the cathodeelectrode 5 via the indium material 4. As a result, the stem 11, theside tube 2, and the faceplate 8 form the vacuum region R inside theelectron tube 1. Next, the getter G is activated by supplyingelectricity through the welding electrode 6 and the flange portion 7. Asa result, the getter G absorbs residual gas in the electron tube 1. Ifgas remains in the space S between the semiconductor device 15 and thestem 11, this gas is not trapped in the space S, but is discharged intothe vacuum region R via the ventilating regions 22 and the openings 21a, enabling the getter G to absorb the gas reliably. Lastly, by removingthe electron tube 1 from the transfer device, the procedure forassembling an electron tube 1, whose inside is in the vacuum state, iscompleted.

Next, the operations of the electron tube 1, produced as describedabove, will be described briefly.

A voltage of −8 kV is applied to the photocathode 9. An electronincidence surface 15A (see FIGS. 2 and 4) of the electron incidence part15 a, which is positioned on the back surface B of the semiconductordevice 15, is set to a ground potential. Electrons are emitted from thephotocathode 9 when light from outside falls incident on thephotocathode 9. The electrons are accelerated by the electric field inthe electron tube 1 and are bombarded into the electron incidencesurface 15A. Numerous electron-hole pairs are formed when theaccelerated electrons lose energy in the silicon substrate of thesemiconductor device 15, yielding a gain of approximately 2,000 times at−8 kV. A high quality image can be obtained on a monitor by electricallyoutputting these multiplied electrons from the semiconductor device 15via the stem pins 14 to the outside monitor.

Since the electron tube 1 of the present embodiment can achieve a highgain, as described above, the signal level of the image is sufficientlyhigher than the noise component of the CCD element 15. Such a high S/Nratio makes it possible to perform single photon imaging. Compared toconventional electron tubes with a built-in microchannel plate (MCP),the electron tube 1 of the present embodiment improves the open arearatio determining efficiency, reduces irregularity in the fluorescentscreen, and prevents conversion loss in a fiber-coupled fiber opticalplate (FOP).

It is noted that when producing normal electron tubes, alkali metalssuch as Na, K, and Cs are introduced into the electron tubes in order toform the photocathode. There is a risk that the alkali metals willpossibly enter the charge transfer section of the semiconductor device15. If the alkali metals reach the SiO₂ gate film, the alkali metalsincrease the fixed charges and the interface state of that portion,remarkably degrading the properties of the semiconductor device 15.However, the electron tube 1 of the present embodiment prevents alkalimetals, introduced into the tube, from entering the device by formingthe SiN layer 106 on the entire part of the top surface of thesemiconductor device 15. Accordingly, the properties of thesemiconductor device 15 are not degraded by preventing alkali metal fromreaching the SiO₂ layer 70, thereby achieving a highly sensitiveelectron tube.

In the electron tube 1 of the first embodiment described above, thespace S formed between the periphery part 15 b and the stem 11 ispartially filled with insulating resin 20. Therefore, the insulatingresin 20 functions as a reinforcing member to prevent the bumps 16 fromseparating from the bump connection portions 19 even when the electrontube 1 is assembled in a high-temperature environment. Further, sincethe insulating resin 20 is not introduced in the electron incidence part15 a, the electron incidence part 15 a is not deformed or damaged due tostress generated when the insulating resin 20 is hardened.

Ventilation is maintained between the semiconductor device 15 and thestem 11 since the insulating resin 20 only partially closes the spacebetween the periphery part 15 b and the stem 11. Accordingly, an airreservoir is not formed between the electron incidence part 15 apositioned at the center of the semiconductor device 15 and the surfaceC of the stem 11, thereby avoiding damage to the electron incidence part15 a that can be caused by air expanding under high temperatures. Inaddition, if gas is emitted from the resin during the high-temperatureprocess to form the photocathode 9, such gas does not become trapped orexpand in the space between the semiconductor device 15 and the stem 11,thereby avoiding damage to the electron incidence part 15 a.

Next, an electron tube according to a second embodiment of the presentinvention will be described with reference to FIGS. 9-11.

FIG. 9 is a cross-sectional view of an electron tube 30 according to thesecond embodiment. The electron tube 30 is a proximity focusing typeelectron tube with a photocathode being positioned near to asemiconductor device. Like parts and components with the electron tube 1of the first embodiment are given the same reference numerals to avoidduplicate description.

Next, the differences between the electron tube 30 of the secondembodiment and the electron tube 1 of the first embodiment will bedescribed with reference to FIGS. 9 and 10.

A supporting substrate 31 is fixed to the top surface of the base plate12 a by an adhesive 32. The supporting substrate 31 is composed ofsilicon material which is the same as the base material (siliconsubstrate) of the semiconductor device 15. The supporting substrate 31forms a portion of a stem 33. A plurality of bump connection portions 34are arranged in two opposing rows on the surface C of the supportingsubstrate 31 in the stem 33. The bump connection portions 34 are formedby depositing Au. A plurality of bumps 16 are formed in two opposingrows on the front surface A of the semiconductor device 15, in the samemanner as in the first embodiment. Each bump 16 is connected to acorresponding bump connection portion 34. Since the supporting substrate31 is formed of the same silicon material as the semiconductor device15, the thermal expansion coefficients of the two components are equalto each other. Therefore, stress deformation caused by heat during thebaking step of the manufacturing process does not occur, preventingdisconnection of the bumps 16. As a result, it is possible tosatisfactorily maintain the connection between the bumps 16 and the bumpconnection portions 34 even without applying the conductive resin 18 tothe bumps 16.

Even with this construction, however, the :bonding strength of the goldbumps 16 decreases as the temperature rises, making it necessary toreinforce the bumps 16 with the insulating resin 20. Therefore, as shownin FIGS. 10 and 11, the space S at the side portions 15 b 2 and 15 b 4in the periphery part 15 b is filled with insulating resin 20 so thatthe insulating resin 20 will encompass each bump 16 in the same manneras in the first embodiment. Also, the side portions 15 b 1 and 15 b 3that have no bumps 16 are not filled with the insulating resin 20.Hence, this construction forms the ventilating regions 22, enabling thespace S between the electron incidence part 15 a and the stem 33 to bein fluid communication with the vacuum region R in the electron tube 1.

A channel or groove 35 is formed on the surface C of the supportingsubstrate 31 in correspondence with each row of bumps 16. Similarly tothe channel 21 of the first embodiment, the channel 35 is provided tocontrol the filling of the insulating resin 20. Here, each channel 35has a width W1 that spans across the border between the correspondingperiphery part 15 b and the electron incidence part 15 a, and a lengthL1 that corresponds to the row of bumps 16. Hence, each channel 35surrounds the border portion 150 between the corresponding side portion15 b 2 or 15 b 4 of the periphery part 15 b and the electron incidencepart 15 a. The channels 35 are formed by a chemical etching processusing KOH solution. The channels 35 thus formed on the surface C of thesupporting substrate 31 provide an outlet into which excess insulatingresin 20 can flow, preventing insulating resin 20 from becoming attachedon the electron incidence part 15 a. Therefore, the space S can beappropriately filled, even when the setting of the amount of insulatingresin 20 and the filling operation is not conducted with high precision.

By setting the height of the space S to about 50 μm, an extremely narrowdimension, the insulating resin 20 can be drawn into the space S by thecapillary effect. In this way, it is easy and efficient to causeinsulating resin 20 to flow into the space S. In this case, it isdesirable to set the depth of the channel 35 to about 0.1 mm in order toblock the insulating resin 20 that flows by the capillary effect. Withthis construction, when the insulating resin 20 drawn through the spaceS by the capillary effect reaches the channel 35, the insulating resin20 collects along the edge of the channel 35 due to surface tension,rather than entering the channel 35. Accordingly, the insulating resin20 can be easily and reliably prevented from attaching the electronincidence part 15 a. Hence, the process of filling the insulating resin20 can be performed easily and appropriately.

As shown in FIG. 11, aluminum (Al) wirings 36 are provided on thesupporting substrate 31 to extend laterally from the respective bumpconnection portions 34. Stem terminals 37 are provided on the base plate12 a in correspondence with the respective aluminum wirings 36. The stemterminals 37 are electrically connected to the respective stem pins 14.Further, the terminal of each aluminum wiring 36 is wire-bonded to thecorresponding stem terminal 37 by an aluminum wire 38.

As shown in FIG. 9, shield electrodes 40 are provided to cover thealuminum wires 38. The base end of each shield electrode 40 isresistance welded to the metal flange 13 to increase a withstand voltagebetween the photocathode 9 and the semiconductor device 15. By coveringthe aluminum wires 38 with the shield electrodes 40, it is possible tobring the photocathode 9 in close to the semiconductor device 15. Thisallows the accelerating voltage to be increased, improving theresolution of images that can be obtained by the semiconductor device15, and further improving the gain of the semiconductor device 15.

Next, an electron tube according to a third embodiment of the presentinvention will be described with reference to FIG. 12.

FIG. 12 is a cross-sectional view showing an electron tube 50 accordingto the third embodiment. Parts and components similar to those of theelectron tube 30 in the second embodiment are given the same referencenumerals to avoid duplicate description.

The differences between the electron tube 50 of the third embodiment andthe electron tube 30 of the second embodiment will be described withreference to FIG. 12.

In correspondence with each row of bumps 16, a channel or groove 51 isformed on the surface C of the supporting substrate 31 which forms aportion of the stem 33.

Similarly to the channel 21 of the first embodiment and the channel 35of the second embodiment, the channel 51 facilitates the operation forfilling the insulating resin 20. In the present embodiment, the channel51 is formed at a position opposing only the periphery part 15 b. Eachchannel 51 has: a length L1 which corresponds to the corresponding rowof bumps 16, and a width W2 which is smaller than the width w′ of theperiphery part 15 b (W2<w′). By forming such a linear channel 51, anyexcess insulating resin 20 can flow into the channel 51, therebyreliably preventing insulating resin 20 from becoming attached on theelectron incidence part 15 a. Therefore, the space S can beappropriately filled with the insulating resin 20 through simple controlof the resin amount.

By setting the height of the space S to about 50 μm, an extremely narrowdimension, the insulating resin 20 can be drawn into the space S by thecapillary effect. In this way, the insulating resin 20 can beefficiently introduced into the space S. If the depth of the channel 35is set to about 0.1 mm in order to block the insulating resin 20 thatflows by the capillary effect, the flow of the insulating resin 20 canbe controlled more efficiently and more reliably.

The electron tube according to the present invention is not limited tothe above-described embodiments, but many modifications and variationsmay be made thereto.

For example, in the above embodiments, the channel 21, the channel 35,or the channel 51 is formed in the.uppermost base plate 12 a or thesupporting substrate 31. However, it is not necessary to form such achannel as shown in an example of FIG. 13. Even without a channel, it ispossible to introduce the insulating resin 20 appropriately whilepreventing the insulating resin 20 from contacting the electronincidence part 15 a, by controlling the amount of insulating resin 20and the filling operation with precision.

Further, a ventilating region 22 may be formed in at least one portionof the periphery part 15 b by leaving at least one portion of the spaceS on the entire circumference of the periphery part 15 b unfilled. Inother words, it is only necessary to form at least one ventilatingregion 22. One ventilating region 22 is sufficient to achieve fluidcommunication between the space S, formed between the semiconductordevice 15 and stem 11 or stem 33, and the vacuum region R. However,smoother ventilation can be achieved by forming a plurality ofventilating regions 22 in the space S as described in the aboveembodiments, and particularly by forming the ventilating regions 22 sothat they oppose with one another with the space S between the electronincident part 15 a and the stem 11 or 33 being sandwiched between theopposing ventilating regions 22.

In the embodiments described above, the insulating resin 20 is filled inthe space S of the periphery part 15 b at positions around the bumps 16.However, the insulating resin 20 may be filled at portions not aroundthe bumps 16. Even when insulating resin 20 is applied at positions notsurrounding the bumps 16, it is possible to adhesively fix thesemiconductor device 15 to the stem 11 or stem 33, thereby reinforcingthe bumps 16 indirectly by maintaining the space S.

For example, the space S can be filled with insulating resin 20 only atpositions corresponding to the four corners of the periphery part 15 b.Or, as shown in FIG. 14, the space S may be filled with insulating resin20 only at positions corresponding to the four corners of the peripherypart 15 b and positions corresponding to the approximate center of thefour side portions 15 b 1-15 b 4. Also in this case, it is not necessaryto form channels similarly to as shown in FIG. 13.

Further, while an insulating resin is used in the above embodiments asthe filling material, any filling material with insulating propertiescan be used. In other words, any material that is normally in a solutionstate or a paste-state and that has insulating properties can be used,if it cures or hardens under heat, if it shrinks according to anappropriate contraction stress during curing, and if it adheres tosurrounding components when contracting. By adhering to both of thesemiconductor device 15 and the stem 11 or stem 33 and contracting, thefiller material can adhesively fix both of the semiconductor device 15and the stem 11 or 33 and can achieve reliable contact and goodelectrical connection between the bumps 16 and the bump connectionportions 19. Examples of such material include water glass andlow-melting glass.

Although a SiN film 106 is formed on the semiconductor device 15 in theembodiments described above, this layer is not necessary.

The electron tube of the present invention is not limited to a proximityfocusing type electron tube, but can also be anelectrostatically-focusing type electron tube.

Industrial Applicabillty

The electron tube according to the present invention can be used in awide range of imaging devices designed for low light intensity region,such as surveillance cameras and night vision cameras.

What is claimed is:
 1. An electron tube, comprising: a side tube; afaceplate provided at one end of the side tube and having a photocathodethat emits electrons in response to incident light; a stem provided atthe other end of the side tube, the stem and the faceplate defining avacuum region, the stem having a bump connection portion on its surface;and a semiconductor device fixed to the stem at its vacuum side, thesemiconductor device having a front surface positioned on the stem sideand a back surface positioned of the faceplate side, the semiconductordevice including an electron incidence part, for receiving electronsemitted from the photocathode, and a periphery part provided at an outerperiphery of the electron incidence part, the electron incidence parthaving a thin plate shape whose thickness is smaller than that of theperiphery part, the periphery part having a bump which protrudes fromthe front surface thereof, the bump being fixed to the bump connectionportion, the bump forming a space between the front surface of thesemiconductor device and the surface of the stem, a filling materialwith insulation property being filled partially in the space at theperiphery part, thereby partially closing the space at the peripherypart.
 2. An electron tube as claimed in claim 1, wherein the fillingmaterial with insulation property is filled in the space at theperiphery part of the semiconductor device except for at least oneposition along the entire circumference of the periphery part, therebyallowing the space at the periphery part to be filled with the fillingmaterial with insulation property except for the at least one position.3. An electron tube as claimed in claim 2, wherein the filling materialwith insulation property is filled in the space at at least one positionalong the entire circumference of the periphery part of thesemiconductor device, with a ventilating region being formed in at leastone position along the entire circumference of the periphery part of thesemiconductor device to provide fluid communication between the spaceand the vacuum region.
 4. An electron tube as claimed in claim 1,wherein the filling material with insulating property includesinsulating resin.
 5. An electron tube as claimed in claim 1, wherein thestem has a supporting substrate on its surface, the supporting substratebeing formed of the same silicon material as a base material of thesemiconductor device, the bump connection portion being provided on thesupporting substrate.
 6. An electron tube as claimed in claim 1, whereinthe bump is made of material that includes gold as a primary component.7. An electron tube as claimed in claim 1, wherein the stem has, at itssurface, a channel for controlling the partial filling of the fillingmaterial with insulating property into the space at the periphery part.8. An electron tube as claimed in claim 7, wherein the channel has awidth that allows the channel to span across a border between theperiphery part and the electron incidence part.
 9. An electron tube asclaimed in claim 7, wherein the channel is formed at a region that facesthe periphery part only.
 10. An electron tube as claimed in claim 7,wherein the channel has a width that allows the channel to span acrossone side portion of the periphery part and the other opposing sideportion of the periphery part.
 11. An electron tube as claimed in claim7, wherein the space formed by the bump has, at the periphery part, aheight small enough to allow the filling material with insulationproperty to generate a capillary effect when the filling material isdrawn into the periphery part, the channel having a depth of an amountthat is capable of stopping the filling material that flows due to thecapillary effect.